EPE Association: EPE 2009 - Topic 14-14 - DS (B): 'Fuel Cells, Emulation and Other Distributed Generation Technologies'

EPE 2009 - Topic 14-14 - DS (B): 'Fuel Cells, Emulation and Other Distributed Generation Technologies'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 14: 'Electrical Energy Generating Systems, Renewable Energy Systems' > EPE 2009 - Topic 14-14 - DS (B): 'Fuel Cells, Emulation and Other Distributed Generation Technologies'

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   A 600KW Electrical Balance Of Plant with LCL Filter for Molten Carbonate Fuel Cell
By KwangSeob KIM, Byung-Ki KWON [View]
[Download]

Abstract: In this paper, a 600KW electrical balance of plant(EBOP) for a molten carbonate fuel cell (MCFC) power plant is introduced. The requirements for EBOP are categorized into as follows : demands on grid interconnection and operational interface with a fuel cell. EBOP has three modes of operation, i.e. grid-connected (GC) mode, grid-independent (GI) mode, and grid-synchronization (GS) mode, to control its output currents, power, and voltages. LCL filter is adopted to meet power qualities demanded by IEEE std. 1547 which defines terms and criterions on interconnection of inverter with grid. EBOP of MCFC is also required to get the ability of fast and smooth transition from GC mode to GI mode to protect a fuel cell under abnormal grid conditions. A 600KW EBOP was tested and installed in a MCFC power plant. Simulations and tests are carried out under various load conditions. Results oftests are presented and show the effectiveness of control algorithm.

   A Fuzzy-Logic Control Strategy for a Hybrid Fuel Cell-Battery System Offering Ancillary Services.
By Christina PAPADIMITRIOU, Nicholas VOVOS [View]
[Download]

Abstract: This paper proposes a fuzzy based local control for a hybrid fuel cell-battery system in order to integrate Distributed Generation (DG) into the distribution grid. Either the grid is connected to the mean voltage side or working in islanded mode, the proposed system offers ancillary services. The performance of the system is evaluated when the grid changes from the connection mode to the islanded operation.

   A New Hybrid Current Control Scheme for Dead-Time Compensation of Inverters with LC filter
By Zhong wei GUO, Fujio KUROKAWA [View]
[Download]

Abstract: This paper presents a new hybrid current control scheme for dead-time compensations and power density optimization of grid-connected dc/ac inverter. A sliding mode controller is designed for compensating the dead-time nonlinear operations, and a PI controller operates in the linear areas. According to the SMC controller output, the unnecessary gate drive signals are removed and the counter side switch can be controlled up to 100\% PWM duty ratio with a smooth transition between different dead time effect modes. With this control scheme, firstly, the influence of dead time can be eliminated, and the harmonic distortion can be greatly reduced. Secondly, the dc-link voltage can be minimized that will contribute to a reduced switching loss and a smaller ripple current. Furthermore, by the eliminations of unnecessary gate drive signals; the switching loss caused by the turn-off tail current can be reduced. The proposed control scheme is verified by simulation and experimental results. It is implemented in a DSP controller, and only some program codes are needed without adding any circuit or components. The reductions of conversion loss, harmonic distortion and ripple current are all achieved in the experimental system. The comparison results between the conventional scheme and the proposed scheme are presented in this paper.

   AC AND DC OUTPUT FUEL CELL HYBRID SYSTEM: DESIGN, BUILDING AND TESTING
By Francisca SEGURA, J. M. ANDUJAR, E. DURÃN [View]
[Download]

Abstract: The hybrid system has been built to supply DC and AC outputs. Voltage levels established on electrical nterconnection points are achieved with several power conditioning stages controlled by Pulse Width Modulation (PWM) and Gain Scheduling techniques. This work means a contribution to few works related to renewable energy distributed generation systems which integrate Gain Scheduling control techniques. Applications of the developed hybrid system can be extended from Auxiliary Power Units (APU) in cars, buses or locomotives to Uninterruptible Power Systems (UPS) in hospitals, nursing-homes, hotels, office buildings or schools.

   Compensation of the low frequency current ripple in single phase grid connected fuel cell power systems
By Salvatore DE CARO, Antonio TESTA, Davide CANIGLIA, Vincenzo ANTONUCCI, Marco FERRARO, Francesco SERGI [View]
[Download]

Abstract: Due their high efficiency, even at partial load and on small size units, fuel cell stacks are suitable for distributed power generation networks,. However, power drawn by single phase grids contains a low frequency oscillation that generates a large ripple on the stack output current. Such a current ripple is able to shorten the fuel cell lifetime, to worsen the stack efficiency and to reduce the available peak power. Therefore, passive and active current ripple reduction techniques have been proposed in the past exploiting bulky electrolytic capacitor banks or expensive active filters. In the proposed paper a new approach is suggested where an active filter is integrated into the converter, without introducing extra power devices. According to the proposed approach the size of the electrolytic capacitor bank can be largely reduced, thus improving the reliability, while lowering costs and size.

   Design Considerations of a Current-fed DC-DC Converter with High Voltage Gain for Fuel Cell Applications
By Andreas AVERBERG, Karl Robert MEYER, Axel MERTENS [View]
[Download]

Abstract: This paper deals with a single phase current-fed full bridge converter with full bridge rectifier. An additional buck converter is used for the clamp circuit. In this way, the clamp voltage can be controlled to an arbitrary value. By a detailed analysis in closed form equations the operating behavior of the dc-dc converter over the full power range can be described. From this analysis three operating modes are identified: discontinuous operating mode (DCM), continuous operating mode (CCM) and buck mode (BM). A boost behavior is received, when operating the converter in DCM and CCM. Operating the converter in BM leads to a buck behavior. Based on the analysis, the impact of the transformerâ€™s winding ratio, its leakage inductance and dimension of input inductor on the converterâ€™s efficiency is emphasized. Out of this, a design procedure is proposed to maximize the converterâ€™s efficiency. Experimental results, taken from a 1:2kW prototype, are shown and compared to the analytical results.

   Electronic device for the emulation of wind systems and analysis of alkaline water electrolysers
By Alfredo URSUA, Eugenio GUBIA, Jesus LOPEZ, Luis MARROYO, Pablo SANCHIS [View]
[Download]

Abstract: This paper proposes an electronic device that emulates the electric power generated by complete wind systems in order to test alkaline water electrolysers under real operating conditions typical of wind regimes. This Wind Emulator has a rated power of 10 kW. It is first validated by means of experimental tests in order to probe its performance concerning quickness, accuracy and reliability. Afterwards, the Wind Emulator is used to test a commercial alkaline electrolyzer from Hydrogenics, whose nominal production rate is 1 Nm3 h-1 so as to obtain its electric characteristic curves. Finally, a wind emulation test is carried out based on real wind data applied to the commercial wind turbine INCLIN6000 from Bornay. By means of this test, the electrolyzer behaviour is analyzed when supplied by a wind energy profile. The results obtained in all the experimental tests have been satisfactory.

   Fixed Pitch Wind Turbine Emulator using a DC Motor and a Series Resistor
By Fernando MARTINEZ RODRIGO, Santiago DE PABLO GOMEZ, Luis Carlos HERRERO DE LUCAS [View]
[Download]

Abstract: It is presented a novel emulator for fixed pitch wind turbines, allowing the laboratory testing of the generator control systems associated with the turbines. The emulator consists of the coupling in series of the following elements: a source of DC voltage, a power resistance and a DC motor. The modification of the input DC voltage has the same effect as the variation of wind speed in a fixed pitch wind turbine. It is included the theoretical foundation of the emulator, the simulations and the experimental results.

   Influence of the Current Ripple on the Hydrogen Fuel Cell Powered Inverter System Efficiency
By Oskars KRIEVS [View]
[Download]

Abstract: Influence of hydrogen fuel cell stack output current ripple caused by a one phase voltage-fed inverter system on efficiency of the fuel cell stack is investigated experimentally. The system includes hydrogen canister, 1.2 kW hydrogen fuel cell module, DC/DC step-up converter and PWM inverter. The system has two DC voltage stages: relatively low and variable voltage on the fuel cell output and stabilized high voltage on the input of the PWM inverter. The electrically isolated voltage-fed pushpull DC/DC step-up power converter with high frequency transformer is found as appropriate for this system from the conventional converters by the following criteria â€“ high efficiency and high power density.

   Integration of Magnetics Components in Step-Up Converter for Fuel Cell
By Pawel KLIMCZAK, Stig MUNK-NIELSEN [View]
[Download]

Abstract: Fuel cell generator is a good example of a high voltage gain application in which dc-dc step-up converter is a critical part. The input voltage of the converter decreases while the output power increases. It reates challenges in design of the converterâ€™s magnetic components. Scope of this paper is integration of the dc inductor and the transformer on a single core. Such integration improves utilization of the core and windings. It leads to size reduction of the converter.

   Laboratory Type PWM Grid Emulator for Generating Disturbed Voltages for Testing Grid Connected Devices
By Ralf LOHDE, Fridrich. W. FUCHS [View]
[Download]

Abstract: This paper presents the design and performance of a test bench to generate grid faults and disturbed grid voltage conditions to test grid connected devices. The test bench is applied to generate different reproducible types of disturbed grid voltages like symmetrical and unbalanced voltage dips, overvoltage, frequency variations and harmonic disturbances. By means of this grid emulator the behavior of active front end converter, grid converter for renewable energy generation systems and also grid connected generators like doubly fed induction generators can be analyzed during voltage disturbances. The laboratory type grid emulator is rated to a nominal power of 30 kVA and is able to handle peak currents up to 150 amps. The nominal output voltage of the grid emulator is 400 volts. The voltage source converter based grid emulator is controlled by means of a dynamically and a static control method depending from the particular test in progress. State space control method has been chosen for good dynamic performance. This paper illustrates the structure of the grid emulator, the design of main components, the dynamic control method applied, and the design of the controller parameters. Furthermore results of the dedicated measurements are presented and discussed.

   Real-Time Power-Hardware-In-the-Loop Facility for Shunt and Serial Power Electronics Benchmarking
By Dan OCNASU, Seddik BACHA, Iulian MUNTEANU, Christian DUFOUR, Daniel ROYE [View]
[Download]

Abstract: Power systems today are undergoing a full mutation, primarily due to the opening of power markets, evolution of technology, exhaustion of natural resources, and dramatic changes in climate. In order to respond to these challenges, countermeasures that leverage power electronic converter technology must be taken at all the levels of the power system: generation, transport and distribution. Due to their innovative character, these solutions require powerful analysis tools, well adapted to the multitude of involved dynamics. The current paper proposes and analyzes the use of a real-time Power Hardware-in-the-Loop (PHIL) simulator for a wind park generation power system, in order to face these complex requirements.

   Simulation package for simulating wind power drives
By Julius LUUKKO, Valtteri HAVERINEN, Vesa RUUSKANEN, Tuomo LINDH, Riku PÃ–LLÃ„NEN, Vesa KÃ„RKKÃ„INEN, Risto TIAINEN, Mikko PÃ„Ã„KKÃ–NEN, Olli PYRHÃ–NEN [View]
[Download]

Abstract: Simulation of static and transient behaviour of wind power plants is important both for grid companies and the power plant suppliers. Simulating a full-power converter based wind power drive includes the simulation of a large electrical circuit. Building such a model with a circuit simulation program requires details which are not necessary from the application point of view. We present an add-on package to Matlab/Simulink, which hides the detailed electrical circuit but nevertheless includes the accurate models inside. A unique feature of this package is its graphical user interface, which concentrates the usage to parts relevant to wind power systems. An efficiency analyzer is also included. This tool analyzes the overall efficiency of a wind power drive train in different operating points using the same model which can be used in technical functionality testing. Simulation results are compared to measurements in a fault ride through test of a full power converter based wind power drive. The correspondence of the results is found satisfactory.

EPE 2009 - Topic 14-14 - DS (B): 'Fuel Cells, Emulation and Other Distributed Generation Technologies'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 14: 'Electrical Energy Generating Systems, Renewable Energy Systems' > EPE 2009 - Topic 14-14 - DS (B): 'Fuel Cells, Emulation and Other Distributed Generation Technologies'
	[return to parent folder]

	A 600KW Electrical Balance Of Plant with LCL Filter for Molten Carbonate Fuel Cell By KwangSeob KIM, Byung-Ki KWON	[View] [Download]
Abstract: In this paper, a 600KW electrical balance of plant(EBOP) for a molten carbonate fuel cell (MCFC) power plant is introduced. The requirements for EBOP are categorized into as follows : demands on grid interconnection and operational interface with a fuel cell. EBOP has three modes of operation, i.e. grid-connected (GC) mode, grid-independent (GI) mode, and grid-synchronization (GS) mode, to control its output currents, power, and voltages. LCL filter is adopted to meet power qualities demanded by IEEE std. 1547 which defines terms and criterions on interconnection of inverter with grid. EBOP of MCFC is also required to get the ability of fast and smooth transition from GC mode to GI mode to protect a fuel cell under abnormal grid conditions. A 600KW EBOP was tested and installed in a MCFC power plant. Simulations and tests are carried out under various load conditions. Results oftests are presented and show the effectiveness of control algorithm.

	A Fuzzy-Logic Control Strategy for a Hybrid Fuel Cell-Battery System Offering Ancillary Services. By Christina PAPADIMITRIOU, Nicholas VOVOS	[View] [Download]
Abstract: This paper proposes a fuzzy based local control for a hybrid fuel cell-battery system in order to integrate Distributed Generation (DG) into the distribution grid. Either the grid is connected to the mean voltage side or working in islanded mode, the proposed system offers ancillary services. The performance of the system is evaluated when the grid changes from the connection mode to the islanded operation.

	A New Hybrid Current Control Scheme for Dead-Time Compensation of Inverters with LC filter By Zhong wei GUO, Fujio KUROKAWA	[View] [Download]
Abstract: This paper presents a new hybrid current control scheme for dead-time compensations and power density optimization of grid-connected dc/ac inverter. A sliding mode controller is designed for compensating the dead-time nonlinear operations, and a PI controller operates in the linear areas. According to the SMC controller output, the unnecessary gate drive signals are removed and the counter side switch can be controlled up to 100\% PWM duty ratio with a smooth transition between different dead time effect modes. With this control scheme, firstly, the influence of dead time can be eliminated, and the harmonic distortion can be greatly reduced. Secondly, the dc-link voltage can be minimized that will contribute to a reduced switching loss and a smaller ripple current. Furthermore, by the eliminations of unnecessary gate drive signals; the switching loss caused by the turn-off tail current can be reduced. The proposed control scheme is verified by simulation and experimental results. It is implemented in a DSP controller, and only some program codes are needed without adding any circuit or components. The reductions of conversion loss, harmonic distortion and ripple current are all achieved in the experimental system. The comparison results between the conventional scheme and the proposed scheme are presented in this paper.

	AC AND DC OUTPUT FUEL CELL HYBRID SYSTEM: DESIGN, BUILDING AND TESTING By Francisca SEGURA, J. M. ANDUJAR, E. DURÃN	[View] [Download]
Abstract: The hybrid system has been built to supply DC and AC outputs. Voltage levels established on electrical nterconnection points are achieved with several power conditioning stages controlled by Pulse Width Modulation (PWM) and Gain Scheduling techniques. This work means a contribution to few works related to renewable energy distributed generation systems which integrate Gain Scheduling control techniques. Applications of the developed hybrid system can be extended from Auxiliary Power Units (APU) in cars, buses or locomotives to Uninterruptible Power Systems (UPS) in hospitals, nursing-homes, hotels, office buildings or schools.

	Compensation of the low frequency current ripple in single phase grid connected fuel cell power systems By Salvatore DE CARO, Antonio TESTA, Davide CANIGLIA, Vincenzo ANTONUCCI, Marco FERRARO, Francesco SERGI	[View] [Download]
Abstract: Due their high efficiency, even at partial load and on small size units, fuel cell stacks are suitable for distributed power generation networks,. However, power drawn by single phase grids contains a low frequency oscillation that generates a large ripple on the stack output current. Such a current ripple is able to shorten the fuel cell lifetime, to worsen the stack efficiency and to reduce the available peak power. Therefore, passive and active current ripple reduction techniques have been proposed in the past exploiting bulky electrolytic capacitor banks or expensive active filters. In the proposed paper a new approach is suggested where an active filter is integrated into the converter, without introducing extra power devices. According to the proposed approach the size of the electrolytic capacitor bank can be largely reduced, thus improving the reliability, while lowering costs and size.

	Design Considerations of a Current-fed DC-DC Converter with High Voltage Gain for Fuel Cell Applications By Andreas AVERBERG, Karl Robert MEYER, Axel MERTENS	[View] [Download]
Abstract: This paper deals with a single phase current-fed full bridge converter with full bridge rectifier. An additional buck converter is used for the clamp circuit. In this way, the clamp voltage can be controlled to an arbitrary value. By a detailed analysis in closed form equations the operating behavior of the dc-dc converter over the full power range can be described. From this analysis three operating modes are identified: discontinuous operating mode (DCM), continuous operating mode (CCM) and buck mode (BM). A boost behavior is received, when operating the converter in DCM and CCM. Operating the converter in BM leads to a buck behavior. Based on the analysis, the impact of the transformerâ€™s winding ratio, its leakage inductance and dimension of input inductor on the converterâ€™s efficiency is emphasized. Out of this, a design procedure is proposed to maximize the converterâ€™s efficiency. Experimental results, taken from a 1:2kW prototype, are shown and compared to the analytical results.

	Electronic device for the emulation of wind systems and analysis of alkaline water electrolysers By Alfredo URSUA, Eugenio GUBIA, Jesus LOPEZ, Luis MARROYO, Pablo SANCHIS	[View] [Download]
Abstract: This paper proposes an electronic device that emulates the electric power generated by complete wind systems in order to test alkaline water electrolysers under real operating conditions typical of wind regimes. This Wind Emulator has a rated power of 10 kW. It is first validated by means of experimental tests in order to probe its performance concerning quickness, accuracy and reliability. Afterwards, the Wind Emulator is used to test a commercial alkaline electrolyzer from Hydrogenics, whose nominal production rate is 1 Nm3 h-1 so as to obtain its electric characteristic curves. Finally, a wind emulation test is carried out based on real wind data applied to the commercial wind turbine INCLIN6000 from Bornay. By means of this test, the electrolyzer behaviour is analyzed when supplied by a wind energy profile. The results obtained in all the experimental tests have been satisfactory.

	Fixed Pitch Wind Turbine Emulator using a DC Motor and a Series Resistor By Fernando MARTINEZ RODRIGO, Santiago DE PABLO GOMEZ, Luis Carlos HERRERO DE LUCAS	[View] [Download]
Abstract: It is presented a novel emulator for fixed pitch wind turbines, allowing the laboratory testing of the generator control systems associated with the turbines. The emulator consists of the coupling in series of the following elements: a source of DC voltage, a power resistance and a DC motor. The modification of the input DC voltage has the same effect as the variation of wind speed in a fixed pitch wind turbine. It is included the theoretical foundation of the emulator, the simulations and the experimental results.

	Influence of the Current Ripple on the Hydrogen Fuel Cell Powered Inverter System Efficiency By Oskars KRIEVS	[View] [Download]
Abstract: Influence of hydrogen fuel cell stack output current ripple caused by a one phase voltage-fed inverter system on efficiency of the fuel cell stack is investigated experimentally. The system includes hydrogen canister, 1.2 kW hydrogen fuel cell module, DC/DC step-up converter and PWM inverter. The system has two DC voltage stages: relatively low and variable voltage on the fuel cell output and stabilized high voltage on the input of the PWM inverter. The electrically isolated voltage-fed pushpull DC/DC step-up power converter with high frequency transformer is found as appropriate for this system from the conventional converters by the following criteria â€“ high efficiency and high power density.

	Integration of Magnetics Components in Step-Up Converter for Fuel Cell By Pawel KLIMCZAK, Stig MUNK-NIELSEN	[View] [Download]
Abstract: Fuel cell generator is a good example of a high voltage gain application in which dc-dc step-up converter is a critical part. The input voltage of the converter decreases while the output power increases. It reates challenges in design of the converterâ€™s magnetic components. Scope of this paper is integration of the dc inductor and the transformer on a single core. Such integration improves utilization of the core and windings. It leads to size reduction of the converter.

	Laboratory Type PWM Grid Emulator for Generating Disturbed Voltages for Testing Grid Connected Devices By Ralf LOHDE, Fridrich. W. FUCHS	[View] [Download]
Abstract: This paper presents the design and performance of a test bench to generate grid faults and disturbed grid voltage conditions to test grid connected devices. The test bench is applied to generate different reproducible types of disturbed grid voltages like symmetrical and unbalanced voltage dips, overvoltage, frequency variations and harmonic disturbances. By means of this grid emulator the behavior of active front end converter, grid converter for renewable energy generation systems and also grid connected generators like doubly fed induction generators can be analyzed during voltage disturbances. The laboratory type grid emulator is rated to a nominal power of 30 kVA and is able to handle peak currents up to 150 amps. The nominal output voltage of the grid emulator is 400 volts. The voltage source converter based grid emulator is controlled by means of a dynamically and a static control method depending from the particular test in progress. State space control method has been chosen for good dynamic performance. This paper illustrates the structure of the grid emulator, the design of main components, the dynamic control method applied, and the design of the controller parameters. Furthermore results of the dedicated measurements are presented and discussed.

	Real-Time Power-Hardware-In-the-Loop Facility for Shunt and Serial Power Electronics Benchmarking By Dan OCNASU, Seddik BACHA, Iulian MUNTEANU, Christian DUFOUR, Daniel ROYE	[View] [Download]
Abstract: Power systems today are undergoing a full mutation, primarily due to the opening of power markets, evolution of technology, exhaustion of natural resources, and dramatic changes in climate. In order to respond to these challenges, countermeasures that leverage power electronic converter technology must be taken at all the levels of the power system: generation, transport and distribution. Due to their innovative character, these solutions require powerful analysis tools, well adapted to the multitude of involved dynamics. The current paper proposes and analyzes the use of a real-time Power Hardware-in-the-Loop (PHIL) simulator for a wind park generation power system, in order to face these complex requirements.

	Simulation package for simulating wind power drives By Julius LUUKKO, Valtteri HAVERINEN, Vesa RUUSKANEN, Tuomo LINDH, Riku PÃ–LLÃ„NEN, Vesa KÃ„RKKÃ„INEN, Risto TIAINEN, Mikko PÃ„Ã„KKÃ–NEN, Olli PYRHÃ–NEN	[View] [Download]
Abstract: Simulation of static and transient behaviour of wind power plants is important both for grid companies and the power plant suppliers. Simulating a full-power converter based wind power drive includes the simulation of a large electrical circuit. Building such a model with a circuit simulation program requires details which are not necessary from the application point of view. We present an add-on package to Matlab/Simulink, which hides the detailed electrical circuit but nevertheless includes the accurate models inside. A unique feature of this package is its graphical user interface, which concentrates the usage to parts relevant to wind power systems. An efficiency analyzer is also included. This tool analyzes the overall efficiency of a wind power drive train in different operating points using the same model which can be used in technical functionality testing. Simulation results are compared to measurements in a fault ride through test of a full power converter based wind power drive. The correspondence of the results is found satisfactory.